CVE-2021-41186: ReDoS vulnerability in parser_apache2
Fluentd collects events from various data sources and writes them to files to help unify logging infrastructure. The parserapache2 plugin in Fluentd v0.14.14 to v1.14.1 suffers from a regular expression denial of service (ReDoS) vulnerability. A broken apache log with a certain pattern of string can spend too much time in a regular expression, resulting in the potential for a DoS attack. This issue is patched in version 1.14.2 There are two workarounds available. Either don't use parserapache2 for parsing logs (which cannot guarantee generated by Apache), or put patched version of parserapache2.rb into /etc/fluent/plugin directory (or any other directories specified by the environment variable FLUENTPLUGIN or --plugin option of fluentd).
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2021-41186?
CVE-2021-41186 has a medium severity rating due to its potential to cause denial of service.
How do I fix CVE-2021-41186?
To fix CVE-2021-41186, you should upgrade Fluentd to a version later than 1.14.1.
What specific versions of Fluentd are affected by CVE-2021-41186?
CVE-2021-41186 affects Fluentd versions from 0.14.14 to 1.14.1.
What is the nature of the vulnerability in CVE-2021-41186?
The vulnerability in CVE-2021-41186 is a regular expression denial of service (ReDoS) caused by a broken apache log.
What components are impacted by CVE-2021-41186?
CVE-2021-41186 specifically impacts the parser_apache2 plugin in Fluentd.